Lately I've been really fond of sticking a fairly wide angle lens to the front of my Mamiya RZ67 and getting in as close as I can to my subjects. The result is always a slightly skewed image with a ton of detail which can be a whole lot of fun to look at and work with.
I am able to do this in part because of the fact that the Mamiya RZ67 can focus in very close thanks to its bellows focusing system. It is for this reason, along with many others, that I still really like the Mamiya (both the RZ67, the RB67, and the C series TLRs) over a lot of other medium format systems out there.